<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style type="text/css">
    .k1{
  width: 500px;height: 500px;background-color: yellow;margin-top: 100px;position: block;

    }
    .k2{
      width: 500px;height: 100px;background-color: red;position: absolute;bottom: 0;
    }
  </style>
</head>
<body>
  <div class="k1">
    <div class="k2"></div>
  </div>
</body>
</html>